Young Female Chimps Use Sticks as 'Dolls'

Study finds correlation with human play

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TUESDAY, Dec. 21, 2010 (HealthDay News) -- Like human children, young chimpanzees appear to play differently depending on their sex, say researchers who spent 14 years observing a chimpanzee community in a national park in Uganda.

The researchers found that both male and female chimpanzee youngsters play with sticks, but females do so more often and sometimes treat the sticks as would mothers caring for their infants.

The study appears in the Dec. 21 issue of the journal Current Biology.

"We thought that if the sticks are being treated like dolls, females would carry sticks more than males do and should stop carrying sticks when they have their own babies," study author Richard Wrangham, of Harvard University, said in a journal news release. "We now know that both of these points are correct."

The findings suggest that the consistently greater tendency across all human cultures for girls to play with dolls is not just the result of sex-stereotyped socialization, but is also influenced by biology, the study authors said.

"This is the first evidence of an animal species in the wild in which object play differs between males and females," Wrangham added.

This is also the first time that stick-carrying as a form of play has been reported in chimpanzees, the study authors noted.

"This makes us suspect that stick-carrying is a social tradition that has sprung up in our community [of chimpanzees] and not others," Wrangham stated in the news release.

If further research shows that this behavior is unique to this community, "it will be the first case of a tradition maintained just among the young, like nursery rhymes and some games in human children," he said. "This would suggest that chimpanzee behavioral traditions are even more like those in humans than previously thought."